Background
Contrary to the generally received wisdom, the historical fact is that the 1990 Elections in Myanmar were arranged as the first stage in the transfer of power which was intended to be completed only after a new constitution had been promulgated and a second round of elections held on the basis of that constitution. The National League for Democracy (NLD) has never acknowledged that such a constitutional process had been set out by the military regime almost a year before the elections were held and tacitly accepted by the NLD when deciding to participate.
Chronology of Statements 1988 - 2003 by Military Spokesmen on the 1990 Elections 

Interview with Khin Aung Myint, Speaker of the Pyidaungsu Hluttaw
Translated from the Yangon Times - October 2011
"I recognize the results of 1990 election. I am explaining the details because I recognize the election results. This incident cannot be abolished and I have no intention to abolish."

• A transcript of the full interview in Burmese is attached. 
• Clause invalidating the 1990 Elections - Article 91 of the Pyithu Hluttaw Law 2010

Election Commission chief says NLD threatened Junta with Nuremburg-style trial
The Irrawaddy -  29 July 2011
According to the head of the Union Election Commission, power was not transferred to Myanmar's main opposition party, the National League for Democracy (NLD), when it won a landslide victory in the 1990 elections because the party allegedly threatened the country's military leaders with a Nuremberg-style war tribunal. The reference was to an interview which the late U Kyi Maung, who is generally credited with the NLD's electoral success in 1990, gave to the Bangkok-based journalist Dominic Faulder and which was published in AsiaWeek of 13 July 1990.

Irrawaddy article, 13 July 1990 interview in AsiaWeek and Maj-Gen Khin Nyunt's remarks

Note by Network Myanmar: There is some doubt whether the remarks were meant to be included at the end of the printed version of the interview. The State Law and Order Restoration Council might not have worried too much if All-India Radio (AIR) had not gone to town on the story and upset the regime.The AIR broadcaster was said to be Daw Mya Than Than Nu, the daughter of former Prime Minister U Nu. [Nuremberg or Nuremburg in English, but Nürnberg in German]

Government disrespects the people's will
The Irrawaddy - 29 May 2011
Suu Kyi has said that ignoring the result of the general election in 1990 was disrespectful to the will of the Burmese people, calling it “a historically inappropriate policy that damaged the image of the country.” Suu Kyi made the comment at headquarters of her party, the National League for Democracy (NLD), in Rangoon’s Sanchaung Township where more than 200 people had gathered on the eve of the 21st anniversary of Burma’s 1990 election. The NLD won a landslide victory in the election in 1990, winning 392 out of 485 parliamentary seats. However, the regime refused to hand over power to the party. Suu Kyi was quoted by reporters in Rangoon as saying: “We have always opposed the rejection of the 1990 election result. It is not because we want power. It is an inappropriate policy because they [government] broke their promise to the people. They gave the people hope, and then broke that hope.” 

Comment by Network Myanmar: The regime took the view that, in demanding the immediate transfer of power prior to the promulgation of a new constitution, it was the NLD which had broken the electoral contract by refusing to accept the constitutional timetable laid down by the State Law and Order Restoration Council (SLORC). The NLD demand for the transfer of power  was rejected by the SLORC which itself  took over the responsibility for organising the drafting of the new constitution themselves instead of leaving it with the NLD as election winners, as they had promised to do so prior to the election.

In an ideal world, the SLORC might well have handed over power straight away, so convincing was the NLD victory at the polls. But an apparent determination by the NLD to stage a confrontation and suggestions by NLD Acting General Secretary U Kyi Maung that there could be a Nuremberg-like trial of the SLORC leaders at which the NLD would nonetheless "play fair" guaranteed that the SLORC would not budge from their position of principle.

Pronouncements, Laws and Regulations

SLORC Declarations Nos. 1 and 2 of 18 September 1988

The Political Parties Registration Law No. 4 of 27 September 1988

The Pyithu Hluttaw [National Assembly] Election Law No 14/89 of 31 May 1989

The  Law No. 10/91 of 10 July 1991 amending the Pyithu Hluttaw Election Law

The Pyithu Hluttaw Election Rules 30 June 1989

The Manifesto of the National League for Democracy dated 6 November 1989

SLORC Declaration No. 1/90 of 27 July 1990

NLD draft Interim Constitution released on 28 July 1990

Gandhi Hall Declaration of 29 July 1990  

The Bo Aung Kyaw Road Declaration of  29 August 1990    

Similarities and contrasts between 1990 and 2010 - Aung Naing Oo
The Irrawaddy - 8 March 2010 

A brief comparison of pre-election conditions, laws in place and military preparations and necessary steps between 1990 and 2010 reveals both strong similarities as well as stark contrasts in the election scenarios.        

"Political Situation of the Union of Myanmar and its Role in the Region."

Col Hla Min, Department of International Affairs and Research, Ministry of Defence

[28th Edition April 2004: Pages 52-53 - the link above is to the almost identical 21st  Edition November 1999: see Pages 17-19]

"There is also another false assumption where her being under house restriction during the election period denied her the right to run for the 1990 election. While under house restriction the Government of Myanmar consented to Ms Suu Kyi's request to contest the election representing Bahan Township Constituency 1 and her name was enrolled on 1 December 1989. Objections were lodged by various individuals and political parties against the permission granted to Ms Suu Kyi to contest the forthcoming elections with reference to the provisions of the Pyithu Hluttaw Election Law of 1989. Legally, granting Ms Suu Kyi the right to contest the elections was found to violate Section 8(b)..... [about permanent residence] 10(e)..... [about allegiance to a foreign power] and 10(h)..... [about links with terrorists]."  
 

Comment by Network Myanmar: Ms Suu Kyi is not currently serving a term of imprisonment in prison, but her residence is restricted under a Directive dated 10 August 2009 from Sen Gen Than Shwe to the Ministry of Home Affairs . Ms Suu Kyi is appealing against her conviction, but from restricted residence, and not while serving a prison term. The National League for Democracy might wish to consider clarifying the status of her restricted residence and thus her eligibility to contest the elections, subject to other criteria, as she is not in fact in prison.

Background Article on the 1990 Elections

The 1990 Elections were characterised more by a failure of communications between the the military government and the political parties than by broken promises.

The Conundrum of the 1990 Elections in Myanmar

A compendium of statements from original sources about the intended purpose of the 1990 Elections held in Myanmar; to be read in conjunction with the above article.

Detailed Results of the 1990 Elections in Myanmar in four Sections, including statistical details of the voting and biographies of the elected representatives

Text of Announcement No. 895 of 30 June 1990 on the final results of the elections 

Transcript of this announcement  

• Section 1    introduction, general statistical review, campaign speeches
• Section 2    detailed statistical results by constituency
• Section 3    brief biographies of elected representatives
• Section 4    background materials, regulations, electoral alliances

• What the late U Kyi Maung, NLD Spokesman, said about "Nuremberg" in 1990  
• 1990 election lessons for NLD - The Irrawaddy 5 October 2009
• A Day to Remember: the 1990 Elections: Eye Witnesses         

Election Commission meets
Working People's Daily - 3 July 1990    

The Election Commission met with Chairmen of the various sub-commissions to review the election. Chairman U Ba Htay presided. Member Saya Chai noted foreign doubts about the possibility of fair elections, which proved unfounded. He said the Election Law did not make reference to any constitution. For the future, he said:

 "A constitution shall prescribe whether the Hluttaw (parliament) will be a bicameral or a unicameral one, its tenure and others. A constitution, which meets the requirements of the country, is to be drawn up in accordance with the wishes of the entire people and to be approved by the majority. A government can be formed only in accordance with the constitution. Only a government that comes into being in accordance with the constitution will be strong. Only such a government will come to power in accordance with the wishes of the people and will have to step down when they no longer like it. It can be found that transfer of power is easy and swift when the constitution is in force. It is believed that the SLORC and the elected Pyithu Hluttaw representatives from parties will hold thorough discussions and go on step by step for coming into being of a constitution which will bring about multi-party democracy and comply with the current situation of the country."

Extract from "AsiaWeek" of 15 June 1990 which predates by six weeks the SLORC Declaration No. 1 of 27 July 1990 and the Gandhi Hall Declaration of 29 July 1990:

The ruling council had counted on a respectable showing by the pro-government National Unity Party. But from the outset SLORC had only vague plans for the assembly, declaring just that the body would need a year or more to draft a new constitution. The generals said that they would hand power to a new civilian government only when the new charter was in place. For its part, the National League had not looked beyond the May polls, given the junta's hardball tactics.......

A possible collision between the party's student-intellectual faction and the so-called old patriotic comrades also needs to be headed off. The younger elements are calling for a tougher line against the government. "We have the absolute sovereignty vested by the people so we don't have to listen to the SLORC", argues a member of the labour bureau. Urges 29-year-old Rangoon senior Ko Ko Gyi: "We have to try to immediately [replace] the government." He is the acting chairman of the All Burma Federation of Student Unions, the country's largest student organisation with which many members of the NLD and other opposition parties are affiliated.

The comrades - retired military officers who rallied around Suu Kyi in late 1988 - favour a more conciliatory approach. They seem to be considering the SLORC's charter-before-government plan. A proposal to set a four-month time frame has been floated. Some say the disagreement between age and youth extends to the central executive committee, which at the moment is composed equally of representatives of the two factions. (Of the five other members in jail or detention, four, including Suu Kyi, some from the younger ranks.) The friction is only exacerbated by the older members' insistence that it is their collective experience that can see the party through the storm.

The committee dismisses talk of a rift. There are no big differences, insists Soe Thein, 45, who is identified with the intellectuals. We have agreed on a more moderate approach. U Kyi Maung announced that the party has already written a draft constitution based on the 1947 charter, which was federal in nature and enshrined a multi-party system. The retired colonel also dismissed talk of a witch hunt against the army for its bloody crackdown on pro-democracy protests in 1988.

But the compromises rankle with some in the rank-and-file.‘There are many students who disapprove of our softer line. Says party youth leader Yan Aung, 28. And new cracks threaten to appear if and when the National League finally takes over. Two years ago this party was nothing observes a diplomat.‘Now everyone wants to be a minister. Other important issues will need to be discussed as well. One is the legal status of the new assembly. The government has not made clear whether those elected in May will become legislators after they have drawn up a new constitution.”

Myanmar: Aspekte der  vorhersehbaren Zukunft (1)
Südostasien aktuell - September 2003 

In German: contains an account of the immediate post-election situation, including the full recognition by the regime of the election results and the decision by the NLD to oppose the constitutional process and to demand the immediate transfer of power.

Myanmar: Aspekte der vorhersehbaren Zukunft (2) 
Südostasien aktuell - March 2004 

 In German: a companion piece to Part 1.